/* RT user.

        Copyright (c) 2002 Roger Larsson <roger.larsson@norran.net>

    This program is free software; you can redistribute it and/or
    modify it under the terms of version 2 of the GNU General Public
    License as published by the Free Software Foundation.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

    Thanks to autor of KSysGuard Chris Schlaeger for borrowed code...
*/

#include <sys/types.h>
#include <sched.h>
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <stdlib.h>

struct request
{
	pid_t pid;
	char _filler[32];
};


int main(int argc, char *argv[])
{
	struct request request;
	FILE *reqf;
	int done=0, loops = 0;

	request.pid = getpid();
	while (!done) {
	    switch (getopt(argc, argv, "?c:p:" )) {
		case 'c':
		    loops = atoi(optarg);
		    break;
		case 'p':
		    request.pid = atoi(optarg);
		    printf("pid %d\n", request.pid);
		    break;
		case '?':
		    printf("%s: [-c|-p pid]\n", argv[0]);
		    printf("\t-c loops\tcheck monitor function by looping\n");
		    printf("\t-p pid\trequest on behalf of other process\n");
		    return 1;
		case -1:
		    // No more options
		    done = 1;
		    break;
	    }
	}

	printf("As long as no monitor runs, execution will sleep here...\n");
	reqf = fopen("/var/named/rt-request", "w");
	if (reqf == NULL) {
	    perror("fopen");
	    return errno;
	}

	printf("policy %d\n", sched_getscheduler(request.pid));


	fwrite(&request, 32, 1, reqf);
	fclose(reqf); // important! (maybe flush?)

	printf("policy %d\n", sched_getscheduler(request.pid));

	// well behaved
	if (request.pid == getpid() && loops > 0) {
	    // Wait until RT prio raised
	    while (sched_getscheduler(request.pid) == 0) {
	    }

	    printf("\nsleep for 3 seconds then start with a\n");
	    printf("busy wait for %d loops (or until prio reduced)\n", loops);
	    printf(" move your mouse!\n");
	    sleep(3);

	    while (--loops > 0 && sched_getscheduler(request.pid) != 0) {
		// someone did listen to my request...
		// assume monitor is running
	    }

	    if (loops == 0)
		printf(" - normal loop finish, to short loop?\n");
	    else
		printf(" - monitor works! (priority got reduced)\n");
	}

	return 0;
}